[amsat-bb] Re: Sats after dark

Mark L. Hammond marklhammond at gmail.com
Fri Nov 19 05:54:49 PST 2010

Hi Dominic,

It's a great question!

If the satellite has batteries that can keep the communications
payload ON, the satellite can continue to support communications
during an eclipse (what we call the time spent in darkness).

Some satellites do not have batteries, so they will support
communications only when in the sun (DO-64 for example).

IO-26  has batteries that are pretty old--yet it continues to operate
through pretty long (20 mins or more) of eclipse each orbit.  So yes,
there are examples where the transmitters work through eclipse (IO-26,
VO-52, etc.).

For AO-51, it's all about power management--both by the bird and by
the command stations.  Right now, AO-51 sees sun all the time. Around
January 1, it will begin to experience ecslipses again.   Its
batteries have lost much of their capacity,  and we expect that there
will be enough power to keep the computer alive during eclipses, but
the transmitters will need to be shut OFF.  The computer and software
onboard AO-51 help do that automatically (for the most part).

Hope that helps!


Mark N8MH

On Fri, Nov 19, 2010 at 8:29 AM, Dominic Hawken <dominic at del.co.uk> wrote:
> Probably a dumb question and still new to this - apologies in advance.
> Am I right in thinking the amateur sats switch comms off when not in
> sight of the sun? Are there any that continue to run in darkness?
> Best,
> Dominic G6NQO
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Mark L. Hammond [N8MH]

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